Patient-specific craniofacial implants

ABSTRACT

Patient-specific craniofacial implants structured for filling bone voids or planned bone voids in the cranium and face as well as for simultaneously providing soft tissue reconstruction and/or augmentation for improved aesthetic symmetry and appearance of face and skull. Pterional or temporal voids or defects generally result from a chronic skull or lateral facial deformity along with a compromised temporalis muscle or soft tissue distortion from previous surgery. When muscle and fat atrophy occurs in the pterion or temporal face, temporal hollowing deformity generally results where there would be soft tissue but for the atrophy. The patient-specific craniofacial implants with dual-purpose herein are configured to have an augmented region adjacent the temporal region of the face and cranium in order to prevent and/or correct any such temporal hollowing deformity and to utilize this newfound space to strategically embed implantable neurotechnologies for improved outcomes.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 16/830,748, filed on Mar. 26, 2020, which is a divisional of U.S.patent application Ser. No. 16/377,455, filed on Apr. 8, 2019, which isa continuation in part of U.S. patent application Ser. No. 16/139,542,filed on Sep. 24, 2018, which is a continuation of U.S. patentapplication Ser. No. 14/958,161, filed on Dec. 3, 2015, which is adivisional of U.S. patent application Ser. No. 13/963,225, filed on Aug.9, 2013. The disclosure of these applications is incorporated herein byreference.

FIELD

The present invention relates to patient-specific craniofacial implantsand methods of designing such implants for filling both bone and softtissue in the temporal region of a patient's head.

BACKGROUND

Certain congenital conditions and acquired deformities related tosurgery, irradiation, and/or trauma may result in varying sized andshaped voids in bone and soft tissue. For example, severe impacts to thehead could leave the frontal, parietal and/or temporal areas of thecraniofacial skeleton in need of repair. Cranial bone voids are commonlyfilled throughout the anterior, middle, and posterior cranial vaults,for example, using autologous bone flaps, standard or customizedalloplastic implants, titanium mesh, biologic absorbable materials,tissue engineered substrates and/or liquid methyl methacrylate in orderto provide much needed cerebral protection. However, in times wheresecondary cranioplasty requires a bone substitute, temporal hollowingneeds to be corrected and/or prevented.

While cranial bone voids present via congenital deformities or traumaticinjuries may be filled using any one or more of the above means toachieve structural soundness, replacement of soft tissue structures thatoverlie the bone void being filled and underlie adjacent skin tissuegenerally has to be accounted for in order to achieve a preferablecosmetic result. Bone flaps, standard or customized alloplasticimplants, titanium mesh, and liquid methyl methacrylate that are used tofill bone voids do not account for soft tissue atrophy in the temporalarea of the skull. Thus, these bone void filling means do not provide anadequate aesthetic reconstruction of this area. The main problems arethat the temporalis muscle and temporal fat pad change shape, thicknessand location following temporary skull bone removal, and therefore, whenthe cranioplasty with custom skull implant is required, one is oftenchallenged by having to mobilize the scarred down muscle and fat fromits abnormal, inferior position and then try to re-attach it to theoutside of currently-designed, patient-specific craniofacial implants.

In many cases where bone is filled in the temporal region, the softtissue loss in this area generally results in concavity referred to astemporal hollowing, as originally described in detail by thesurgeon-inventor in 2015 [“Quantitative analysis of dual-purpose,patient-specific craniofacial implants for correction of temporaldeformity. Operative Neurosurgery 11(2):205-12” and “Craniofacialreconstruction with poly (methyl methacrylate) customized cranialimplants. Journal of Craniofacial Surgery 26(1):64-70.”) This deformingasymmetry reflects a deficiency in the bulk of the temporalis muscle oroverlying temporal fat pad along the upper lateral face. Many patientswho have undergone neurosurgical procedures that damage the integrity ofthe temporalis muscle during temporal or pterional craniotomy surgery inthe temporal area are left with this concavity. Both aesthetic andreconstructive procedures that violate the temporal fat pad may alsoresult in temporal hollowing. As such, the area of concern is a directdeformity related to a few etiologies such as temporalis muscledisplacement or foreshortening from previous surgery, temporal fat padatrophy, or soft tissue contraction from irradiation or aging. Thus,traditional implant methods require the surgeon to mobilize thesescarred tissues off of the brain.

In patients with the common temporal hollowing, the top or cephalad partof the deformity is generally a concave depression due to the missing,above-mentioned etiologies. In addition, directly underneath andneighboring this concave depression is a convex bulge (directly cephaladto the zygomatic arch) that often originates from a displaced temporalismuscle. In some common instances, the temporalis muscle cannot bere-inserted since the bone flap is unable to be placed back intoposition, thereby leaving an absent fixation point adjacent the temporalcrest. This not only accentuates the neighboring concave deformityabove, it sometimes causes dynamic distortion during chewing since thetemporalis muscle is involved with mastication.

Other reasons for the cephalad deficiency, or other head deformities,may entail temporal fat pad wasting, which is a defined layer ofanatomical fat between the scalp and the skull which adds to the normalbulk of one's temporal region. It is often a sign of youthfulness. Manypatients who have undergone neurosurgical and/or temporal procedures maylose the integrity of the temporalis muscle during temporal or pterionalcraniotomy surgery. Both aesthetic and reconstructive procedures thatviolate the temporal fat pad, such as coronal incisional approaches, forinstance, may also result in temporal hollowing deformities, which canhappen if a surgeon devascularizes the area with dissection or if thearea has received irradiation or tissue resection for oncologicaltreatment.

Numerous techniques have been described to augment the temporal area,including the placement of various standard or customized alloplasticimplants, titanium mesh, free fat grafts, dermal grafts, tissueengineered substrates, the injection and onlay of various absorbable andpermanent materials, loco-regional flaps, and, in some instances, freetissue transfer with microscopic technique. Temporal augmentation canrestore the preoperative appearance of these patients; however, suchaugmentation is generally performed in a subsequent procedure after aninitial procedure of filling a bone void in this area. Thus, thesesolutions are problematic because a revision surgery is generallyrequired to correct the deformity, and the patient will likely exhibitaesthetic asymmetry prior to the revision surgery. There thus exists aneed for a patient-specific cranial implant that provides both bonyreconstruction and soft tissue reconstruction such that one or morerevision surgeries will generally not be necessary. All previousimplants follow the inferior, inward tapering of the normal temporalbone.

SUMMARY

As used herein, when referring to bones or other parts of the body, theterm “superior” or “cephalad” means upper or top, and the term“inferior” or “caudal” means lower or bottom. The term “posterior” meanstowards the back of the body, and the term “anterior” means towards thefront part of the body or the face. The term “medial” means toward themidline or center of the body, and the term “lateral” means away fromthe midline or outside of the body.

The patient-specific, dual-purpose temporal implants of the presentinvention are designed to fill a void in the skull while alsosimultaneously augmenting the pterional/temporal area. Preferably,alloplastic material is used in the construction of suchpatient-specific temporal implants. The mechanical properties of thealloplastic material used to construct these implants will allow them tocover the void and to recreate the soft tissue bulk that is preferablypresent in the temporal area prior to any injury and/or atrophyoccurring in a patient. The patient-specific implants of the presentinvention are designed to fill a cranial void while also restoringaesthetic symmetry by augmenting the temporal area of the skull tocounter temporal hollowing. Therefore, the patient-specific cranialimplants of the present invention may be used to replace a bony voidleft by a craniotomy either as a preemptive or prophylactic solution toaddressing aesthetic asymmetry that may occur due to atrophy of temporalmuscle or overlying fat pad of the bony void.

A first aspect of the present invention is a method of designing apatient-specific craniofacial implant for filling a void in a patient'sskull and for simultaneously replacing soft tissue comprises firstcreating a three dimensional model of the skull having the void, thencreating a preliminary implant model configured to replace the void inthe skull, and then creating an updated implant model by augmenting anouter contour of the preliminary implant model to account for softtissue loss or displacement in a temporal area such as the pterionalregion of the skull overlying at least a portion of the bony void. Asecond aspect is to create a “temporal trim” or virtual window toprevent muscle impingement when using the implant in an overlay position(above the scarred down tissue) within the temporal fossa.

In one embodiment of this first aspect, tomographic images of the skullof the patient are taken in order to create the three-dimensional modelof the skull including the void. The preliminary model is created bymirroring contralateral bone of the void about a sagittal plane of thepatient. If the defect is bilateral, normal variations of soft tissue tohard tissue variance may be assessed by industry standards and utilizedfor unilateral or bilateral temporal implant fabrication. Suchassessments may be made as gender-specific for males and females sincethey are known to have different gender-specific anthropometrics.

In another embodiment of this first aspect, creating a three dimensionalof the skull having the void may include taking two-dimensional orthree-dimensional photographs from various views for confirmation ofaesthetic deformity size and/or shape of the void. It may also includecreating a “single-stage custom implant” design. This type of noveldesign would allow the surgeon to virtually plan an oncologicalresection of a skull tumor (or brain tumor invading a skull) and addseveral centimeters of extra implant material around the edges. Thistype of advance would allow one to resect a skull tumor and thenimmediately use a dual-purpose, patient-specific craniofacial implant torestore the oncological defect to proper symmetry in hopes of avoiding apost-operative temporal deformity.

In another embodiment of this first aspect, augmenting the outer contourof the preliminary implant model comprises providing a firstcross-sectional view of the preliminary implant model in a coronalplane, providing on the first cross-sectional view a vertical linetangent to a most lateral portion of a zygomatic arch of the skull ofthe patient, and providing on the first cross-sectional view a contourline from a temporal crest of the skull until the contour lineintersects the vertical line tangent to the most lateral portion of thezygomatic arch in the first cross-sectional view, the contour linerepresenting a first portion of the augmented outer contour of thepreliminary implant model. Following this embodiment, the implant modelmay be trimmed accordingly using a vector spanning between the zygomaticprocess of the temporal bone and the zygomatic-frontal suture of thelateral orbital rim to allow placement and positioning over the scarreddown temporalis muscle.

In yet another embodiment of this first aspect, augmenting the outercontour of the preliminary implant model further comprises providing asecond cross-sectional view of the preliminary implant model in acoronal plane, providing on the second cross-sectional view a verticalline tangent to a most lateral portion of a zygomatic arch of the skullof the patient, and providing on the second cross-sectional view acontour line from a temporal crest of the skull until the contour lineintersects the vertical line tangent to the most lateral portion of thezygomatic arch in the second cross-sectional view, the contour linerepresenting a second portion of the augmented outer contour of thepreliminary implant model. The coronal plane of the firstcross-sectional view is more posterior than the coronal plane of thesecond cross-sectional view.

In still yet another embodiment of this first aspect, augmenting theouter contour of the preliminary implant occurs in a plurality ofcross-sectional views in the coronal plane.

In still yet another embodiment of this first aspect, augmenting theouter contour of the preliminary implant occurs in a plurality ofcross-sectional views in an axial plane.

In still yet another embodiment of this first aspect, augmenting theouter contour of the preliminary implant occurs in a plurality ofcross-sectional views in a sagittal plane.

In still yet another embodiment of this first aspect, thepatient-specific craniofacial implant is manufactured from alloplasticand/or absorbable biologic materials selected from one member of a groupconsisting of polymethylmethacrylate (PMMA), polyetheretherketone(PEEK), porous high-density polyethylene (MedPor), or any otherFDA-approved biomaterial. Other biologic materials or tissue-engineeredsubstrates may also be used in both allograft and xenograft origin usingthe patient-specific craniofacial implant design processes describedherein.

A second aspect of the present invention is a craniofacial implantcomprising a base portion having an outer surface curved in a medial tolateral direction, a superior to inferior direction, and a posterior toanterior direction, and a curved augment portion protruding outwardlyfrom the outer surface of the base portion in the medial to lateraldirection to restore proper appearance anywhere along the temporalskeleton when both a hard tissue deformity and soft tissue deformityco-exist. The craniofacial implant of the present invention could alsobe designed for soft-tissue only defects, providing the surgeon a newmethod to camouflage asymmetries—both from congenital and acquiredetiologies.

In one embodiment of this second aspect, the curved augment portion ofthe craniofacial implant has an outer surface curved in the medial tolateral direction, the superior to inferior direction, and the posteriorto anterior direction.

In another embodiment of this second aspect, the outer surface of thebase portion and the augment portion has a first radius of curvature inthe medial to lateral direction, and wherein the first radius ofcurvature of the base portion is larger than the first radius ofcurvature of the augment portion.

In yet another embodiment of this second aspect, the outer surface ofthe base portion and the augment portion has a second radius ofcurvature in the superior to inferior direction, and wherein the secondradius of curvature of the base portion is larger than the second radiusof curvature of the augment portion.

In yet another embodiment of this second aspect, the outer surface ofthe base portion and the augment portion has a third radius of curvaturein the posterior to anterior direction, and wherein the third radius ofcurvature of the base portion is larger than the third radius ofcurvature of the augment portion.

In yet another embodiment of this second aspect, the outer surfaces ofthe base portion and the augment portion are convex.

In still yet another embodiment of this second aspect, the base portionand the augment portion each have concave inner surfaces.

In still yet another embodiment of this second aspect, the base portionhas a lateral side that forms a perimeter of the craniofacial implant.

In still yet another embodiment of this second aspect, the augmentportion has a lateral side that forms a portion of a perimeter of thebase portion.

In yet another exemplary embodiment of the second aspect, the temporalportion has an anterior extension that forms an onlay prosthesis (asopposed to a full-thickness defect replacement prosthesis) used fortemporal deformity prevention and/or correction for which may evenextend to the lateral orbital rim and cover areas of intact skull.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the subject matter of the presentinvention and the various advantages thereof can be realized byreference to the following detailed description in which reference ismade to the accompanying drawings in which:

FIG. 1A is a perspective view of a patient's face exhibiting temporalhollowing deformity in the pterional or temporal region of the skull orface.

FIG. 1B is a perspective view of the patient's face of FIG. 1A with arepaired pterional or temporal region such that the temporal hollowinghas been corrected.

FIG. 2 is a perspective view of a patient's skull or lateral faceexhibiting a large bone void predominately positioned in the temporallobe thereof.

FIG. 3A is a frontal view of one embodiment of a patient-specificcranial implant of the present invention designed to fill a bone void ina skull of a patient and to simultaneously correct co-existing temporalmuscle/fat deficiencies contributing to deformity.

FIG. 3B is a lateral view of an outer surface of the patient-specificcranial implant of FIG. A.

FIG. 3C is a lateral view of an inner surface of the patient-specificcranial implant of FIG. 3A.

FIG. 4A is a 3D reconstruction of a patient-specific cranial implant ofthe present invention having filled a void in the skull or lateral faceof a patient, the patient-specific cranial implant having an augmentedportion projecting outwardly from a base portion.

FIG. 4B is a coronal cross-section of the 3D reconstruction of FIG. 4Ataken along the section line shown in FIG. 4A, the cross-section showingthe relationship between the base portion and the augmented portion ofthe patient-specific cranial implant.

FIG. 5A is a 3D reconstruction of the patient-specific cranial implantof FIG. 4A wherein the augmented portion thereof is shown having an areaapproximately the area of the box with arrows overlying the implant.

FIG. 5B is a coronal cross-section of the 3D reconstruction of FIG. 5Ataken along line 5B thereof showing the location of the most lateralportion of the augmented portion of the patient-specific cranialimplant.

FIG. 6A is a lateral view of the 3D reconstruction of thepatient-specific cranial implant.

FIG. 6B is a frontal view of the 3D reconstruction of thepatient-specific cranial implant shown in FIG. 6A.

FIG. 7A is a lateral view of a 3D reconstruction of another embodimentof a patient-specific cranial implant having a base portion and at leastone augmented portion.

FIG. 7B is a coronal cross-section of the 3D reconstruction of FIG. 7Ataken along line 7B thereof, the cross-section showing the configurationof the base portion and the augmented portion at a posterior location ofthe pterional or temporal region of the skull and face.

FIG. 7C is another lateral view of a 3D reconstruction of thepatient-specific cranial implant of FIG. 7A.

FIG. 7D is a coronal cross-section of the 3D reconstruction of FIG. 7Ctaken along line 7D thereof, the cross-section showing the configurationof the base portion and the augment portion at a central location of thepterional or temporal region of the skull and face.

FIG. 7E is yet another lateral view of a 3D reconstruction of thepatient-specific cranial implant of FIG. 7A.

FIG. 7F is a coronal cross-section of the 3D reconstruction of FIG. 7Etaken along line 7F thereof, the cross-section showing the configurationof the base portion and the augmented portion at an anterior location ofthe pterional or temporal region of the skull and face.

FIG. 8A is a frontal view of a 3D reconstruction of the patient-specificcranial implant shown in FIG. 7A.

FIG. 8B is an axial cross-section of the 3D reconstruction of FIG. 8Ataken along line 8B thereof, the cross-section showing the configurationof the base portion and the augmented portion at a superior location ofthe pterional or temporal region of the skull and face.

FIG. 8C is another frontal view of a 3D reconstruction of thepatient-specific cranial implant of FIG. 7A.

FIG. 8D is an axial cross-section of the 3D reconstruction of FIG. 8Ctaken along line 8D thereof, the cross-section showing the configurationof the base portion and the augmented portion at a central location ofthe pterional or temporal region of the skull and face.

FIG. 8E is yet another frontal view of a 3D reconstruction of thepatient-specific cranial implant of FIG. 7A.

FIG. 8F is an axial cross-section of the 3D reconstruction of FIG. 8Etaken along line 8F thereof, the cross-section showing the configurationof the base portion and the augmented portion at an inferior location ofthe pterional or temporal region of the skull and face.

FIG. 9A is an exemplary view of a pre-existing skull and facial defectin need of a customized cranial implant.

FIG. 9B is an exemplary diagram of a custom cranial implant and methodof implantation.

FIG. 9C is an exemplary diagram of a custom cranial implant asimplanted.

FIG. 10A is an exemplary view of a pre-existing skull and facial defectin need of a customized cranial implant.

FIG. 10B is an exemplary diagram of a custom cranial implant and methodof implantation.

FIG. 10C is an exemplary diagram of a custom cranial implant asimplanted.

FIG. 10D is an exemplary post operation CT scan showing a cranialimplant as implanted.

FIG. 11A is an exemplary view of a pre-existing skull and facial defectin need of a customized cranial implant.

FIG. 11B is an exemplary diagram of a custom cranial implant asimplanted.

FIG. 11C is an exemplary view of a pre-existing skull and facial defectin need of a customized cranial implant.

FIG. 11D is an exemplary diagram of a custom cranial implant asimplanted.

FIG. 12A is an exemplary view of a pre-existing skull and facial defectin need of a customized cranial implant.

FIG. 12B is an exemplary view of a pre-existing skull and facial defectin need of a customized cranial implant.

FIG. 12C is an exemplary view of a pre-existing skull and facial defectin need of a customized cranial implant.

FIG. 13A is an exemplary diagram of a custom cranial implant asimplanted.

FIG. 13B is an exemplary diagram of a custom cranial implant asimplanted.

FIG. 13C is an exemplary diagram of a custom cranial implant asimplanted.

DETAILED DESCRIPTION

FIG. 1A is a perspective view of a patient's face 100 exhibitingtemporal hollowing 120 in the pterional or temporal region of the skulland face of the patient. The size, shape and location of such temporalhollowing deformity of a patient may differ based on patient's anatomyas well as the type of injury and/or the amount of tissue atrophyincurred by the patient in this region.

FIG. 1B is a perspective view of the patient's face with a repairedpterional or temporal region such that the temporal hollowing deformityhas been corrected and is no longer present. After an initial surgery tocorrect a bony void is performed, a subsequent procedure using apterional graft, liquid PMMA, dermal filler, absorbable material ortissue engineered substrate, for example, may be performed in order torepair the soft tissue defect. The subsequent procedure may be conductedvia injection of PMMA percutaneously into this region or by placing apterional flap through a small incision made in the skin. However, apatient will likely exhibit aesthetic asymmetry between the time of theinitial surgery and the subsequent revision surgery to correct thetemporal hollowing deformity shown in FIG. 1A. Soft tissuereconstruction will change with the respect to time and is suboptimalversus a solid, computer-designed implant with stable and durabledesign/shape. The patient-specific cranial implants and methods ofdesigning such implants of the present invention together providesimultaneous customized hard tissue (i.e. bony) reconstruction and softtissue (i.e. fat/muscle) reconstruction in a single procedure approachsuch that temporal hollowing deformity is avoided and revisionprocedures will not be required.

FIG. 2 is a perspective view of a patient's skull 200 exhibiting a largeirregularly shaped bone void 210 predominately positioned in thetemporal lobe thereof. FIGS. 3A-3C show one embodiment of apatient-specific cranial implant 300 of the present invention designedto fill a bone void, such as shown in FIG. 2, for example.Patient-specific cranial implant 300 includes a perimeter 320 configuredto contact a perimeter 220 of bone void 210 when patient-specificcranial implant 300 is coupled to bone void 210 in a preoperativelyplanned position. Upon coupling of patient-specific cranial implant 300to bone void 210, plates, fasteners and/or adhesive glue, for example,may be used around perimeters 220, 320 of bone void 210 and implant 300,respectively, in order to fix the position of implant 300 with respectto bone void 210. A description of such plates and fasteners used tocouple a patient-specific implant to a perimeter of a bone void is shownand described in the surgical protocol titled “Stryker CMF CustomizedImplant PEEK,” the disclosure of which is incorporated by referenceherein in its entirety. Of note, the implants from this surgicalprotocol (as shown) are designed to have contact within the skull defectand complete 360-degree fixation once the temporalis muscle is removedfrom its scarred position on top of the brain. They are not designed toflare outwards and/or to have a dual-purpose design other than to simplyreplace the missing temporal bone.

Implant 300 includes a base portion 340 and an augment portion 360. Baseportion 340 includes a convex outer surface 342 and a concave innersurface 344. Outer and inner surfaces 342, 344 of base portion 340 arepreferably curved in a superior to inferior direction, a posterior toanterior direction, and a medial to lateral direction. Augment portion360 protrudes outwardly from base portion 340 in the medial to lateraldirection. Augment portion 360 includes a convex outer surface 362 thatis also preferably curved in the superior to inferior direction, theposterior to anterior direction, and the medial to lateral direction.

Base portion 340 and augment portion 360 each have a first radius ofcurvature in the superior to inferior direction, a second radius ofcurvature in the posterior to anterior direction and a third radius ofcurvature in the medial to lateral direction. The first, second andthird radii of curvature of the base portion 340 are all larger than thefirst, second and third radii of curvature of the augment portion 360,respectively. Therefore, base portion 340 is flatter and not as steeplyshaped as augment portion 360. The radii of curvature are generally notconstant along any one direction for each of the base portion 340 andaugment portion 360.

Augment portion 360 has a lateral side 370 that preferably forms aportion of a perimeter 350 of base portion 340. The location of augmentportion 360 with respect to base portion 360 is such that lateral side370 of augment portion 360 preferably forms a portion of perimeter 320of implant 300 along with perimeter 350 of base portion 340.

When cranial implant 300 is implanted, the most lateral portion of outersurface 362 of augment portion 360 is preferably located on a linetangent to the most lateral portion of the zygomatic arch, the linebeing substantially parallel to the sagittal plane of the patient.Augment portion 360 also extends as far posteriorly as it doessuperiorly so that an area of augment portion is roughly square. Theaugmented portion terminates at a limit known and described as atemporal trim line—which is a consistent vector spanning the zygomaticprocess of the temporal bone and the zygomatic-frontal suture line ofthe lateral orbital bone.

A method of designing a patient-specific craniofacial implant, such ascranial implant 300, for filling a void in a skull or face of a patientand for replacing soft tissue is shown in FIGS. 4A-6B. A tomographicscan such as a computed tomography (“CT”) scan of a patient with alateral cranial or facial defect that fully or partially extends intothe pterional or temporal region of the skull and face is first taken.Off the shelf CT segmentation software is then used to create a threedimensional (“3D”) model of the patient's cranium including the lateralcranial or facial defect. A patient-specific craniofacial implant isthen designed using computer aided design (“CAD”) software. Thepatient-specific 3D implant will fill the bony void left by acraniotomy, for example, and also augment the visible temporal portionsof the patient's head. When and if needed or desired, an additionalextension of thin material can extend from the anterior boundaries ofthe implant as an overlay (above intact skull or facial bone) and abutthe lateral orbital rim along the temporal fossa area.

In some further exemplary embodiments, an augmentation of the outercontour of the preliminary implant model to account for facial softtissue loss overlying at least a portion of the bony void may furtherinclude the creating of a purposeful gap (i.e. temporal trim). The gapmay be formed as a consistent and valuable “temporal trim” to avoidpainful compression of the temporalis muscle left undisturbed underneaththe implant, as opposed to suspending it on the outside of the implantwhich is done in normal fashion. Further, an extra portion of materialmay be created or used as an added extension that abuts the lateralorbital rim to the extent of the zygoma's later projection, which isoutside the confines of the actual full-thickness skull defect.

Using the CAD software, a preliminary implant model 400 is designed bymirroring contralateral bone of the lateral cranial or facial defect.Generally, the contralateral bone is mirrored off of the centralsagittal plane 410 as shown in FIG. 4B of a patient's skull or face inorder to define the size, shape and location of preliminary implantmodel 400 with respect to the cranial or facial defect. Models ofdeformed or missing segments of internal structures, such as a lateralcranial and facial defect, may also be constructed from coordinate dataspecifying the deformed or missing segment that is derived fromrepresentations of a normal mirror image segment of the structure. Forexample, coordinate data defining a mirror image segment of a structureis useful in the construction of an implantable prosthetic inlay that isto replace a missing segment of a generally symmetrical internalanatomic structure as shown and described in U.S. Pat. No. 4,436,684 toWhite entitled, “Method of Forming Implantable Prosthesis forReconstructive Surgery,” the disclosure of which is hereby incorporatedby reference in its entirety. In instances where bilateral deformitiesexist, the dual-purpose implants of the present invention may be atleast partly designed using standard gender-specific dimensions.

While preliminary implant model 400 may be designed using any one ormore of the above described methods, it represents a traditionalcustomized implant that does not account for soft tissue in thepterional/temporal region. It can also have a single-use design toreplace any and all missing cranial bone, as opposed to a dual-purposedesign for which has thin onlay extensions nearby to adjust for anymissing soft tissue. It also doesn't account for leaving the temporalmuscle down against the brain and requires the surgeon to mobilize themuscle off of the brain at time of placement. In a method of the presentinvention, preliminary implant model 400 is used as a guide duringsubsequent design steps. The outer contour 420 of preliminary implantmodel 400 is augmented in order to account for the soft tissue loss.This novel shape and design allows for the surgeon to position theimplant above the scarred down muscle by way of a “temporal trim window”design.

Preliminary implant model 400 is designed to have a perimeter thatcontacts the entire perimeter of the bone void. Augment portion 500 isdesigned to augment the pterion in order to counter the effects oftemporal hollowing deformity. Careful attention is made not to includeexcess material inferiorly which may contribute to mandibularinterference known as trismus. This excess material is removed at thetemporal trim line on a vector consistent between two reliableanatomical landmarks, the zygomatic process of the temporal bone and thezygomatic-frontal suture line along the lateral orbital rim. The CTcoronal cross section of FIG. 4B shows the difference betweenpreliminary implant model 400 and an updated implant model includingaugment portion 500. In some design processes, augment portion 500 mayonly project outwardly from preliminary implant model 400 such that itdoes not span the entire length of a bone void, and therefore does notcontact the entire perimeter of the bone void as does the preliminaryimplant model. By not contacting the inferior bone edge, the designallows for an augmented design and does not mirror the temporal bone asit tapers inward. As can be seen in FIG. 4B, for example, augmentportion 500 is not symmetric to contralateral bone as is preliminaryimplant model 400. Together, preliminary implant model 400 and augmentportion 500 form an updated implant model 600 as shown in FIG. 4A.Preliminary implant model 400 has a first volume and augment portion 500has an additional volume. With the addition of the volume of augmentportion 500 to the first volume of preliminary implant model 400,updated implant model 600 therefore has a second volume greater than thefirst volume. This figure also includes a directional legend with arrowsin three dimensions. S, I, M, L, P and A on this legend, and any otherlegend in the drawings, stand for superior, inferior, medial, lateral,posterior and anterior, respectively. Most of the bulk reproduction ofthe soft tissue in the pterion or temporal region, which is representedby augment portion 500, occurs at the anterior, lateral, inferiorportion of the temporal skull and face.

In determining the location of the most lateral portion of the outersurface of augment portion 500, the preliminary implant model 400 isextended laterally away from sagittal plane 410, for example, until theouter surface of augment portion 500 meets the most lateral portion ofthe zygomatic arch 550 of the patient as shown in FIG. 5B. The mostlateral portion of the zygomatic arch is depicted by vertical line 540in the coronal cross section shown in FIG. 5B. In the coronal plane, thetemporal region of the preliminary implant model is augmented by drawinga substantially straight or slightly curved line 560 from the temporalcrest 530 until line 560 intersects vertical line 540 adjacent the mostlateral portion of the zygomatic arch 550. Temporal crest 530 is locatedat the point where there is a change in tangency of the pterional skullas pertinent in the present scenario. Of note, various other areas ofthe temporal (i.e. pterional) skeleton could be assessed fordual-purpose reconstruction. This process is preferably repeated inseveral different two dimensional (“2D”) coronal cross-sections. Theupdated implant models created in the 2D cross-sections are thencombined using the CT segmentation software in order to create the 3Dupdated implant model shown in FIGS. 6A-6B, for example.

As shown in FIGS. 6A-6B, augment portion 500 extends posteriorly fromthe lateral orbital rim 575 to a vertical line 580 perpendicular to thesagittal plane drawn through the external acoustic meatus 585. Augmentportion 500 should extend as far posteriorly as it does superiorly sothat the augmented area is roughly square as shown in FIG. 5A. Theaugmented area is roughly outlined by box 570 overlying updated implantmodel 600 in FIG. 5A.

FIGS. 7A, 7C, and 7E are a series of lateral views of a 3Dreconstruction of one embodiment of an updated implant model 600implanted in a model of a bone void of a patient's skull and facialbones 610, each of these views including a section line 7B, 7D, and 7F,respectively. Section lines 7B, 7D, and 7F are each situated atdifferent locations on the 3D models. Section line 7B is located in aposterior region, section line 7D is located in a central region, andsection line 7F is located in an anterior aspect of the pterional ortemporal region of the patient's skull and face 610 in these lateralviews. FIGS. 7B, 7D and 7F are coronal cross-sectional views thatcorrespond to FIGS. 7A, 7C and 7E, respectively. Each of these coronalcross-sectional views show updated implant model 600 including apreliminary implant model 700 and an augment portion 800. As can be seenmost clearly in FIG. 7D, augment portion 800 is not symmetric tocontralateral bone as is preliminary implant model 700. Most of the bulkreproduction of augment portion 800 is created in this central region ofthe pterion or temporal region of the lateral face.

FIGS. 8A, 8C, and 8E are a series of frontal views of updated implantmodel 600 each having a section line 8B, 8D, and 8F, respectively.Section lines 8B, 8D, and 8F are each situated at different locations onthe 3D models. Section line 8B is located in a superior region, sectionline 7D is located in a central region, and section line 8F is locatedin an inferior aspect of the pterional or temporal region of thepatient's skull and face in these lateral views. FIGS. 8B, 8D and 8F areaxial cross-sectional views that correspond to FIGS. 8A, 8C and 8E,respectively. Each of these axial cross-sectional views shows thedifference between preliminary implant model 700 and an updated implantmodel including augment portion 800. As can be seen most clearly in FIG.8D, augment portion 800 is not symmetric to contralateral bone as ispreliminary implant model 700. It is designed and modified specificallyto make up for the soft tissue discrepancy. In other words, it can beused for temporal hollowing deformity prophylaxis and/or secondarycorrection.

Each patient-specific cranial implant of the present invention will becustomized to fit the unique bony void and individual anthropometry ofthe patient, and therefore, the design inputs described above may beadjusted as needed. For example, with respect to bilateral deficits, thedual-purpose implants can be fabricated used gender-specificanthropometric norms. In addition, in instances of skull tumors or braintumors invading skull in need of oncological resection (where the actualskull or facial bone defect has yet to be created), these types ofdual-purpose implants could be designed using a single-stage approach.For example, if a neurosurgical patient were to present with a largebrain and/or skull tumor invading the greater sphenoid wing (the part ofthe skull located behind the eyeball and part of the orbital skeleton),then resection and reconstruction is quite difficult because, without anexact reconstruction following tumor removal, the eyeball willundoubtedly shift either forward (exophthalmos) or backward(enophthalmos) after the combined tumor resection/reconstructionsurgery, and the patient will have a major deformity which is verydifficult to fix secondarily. Thus, it would be best for the patient andmore desirable to prevent, rather than fix this deformity secondarily).Therefore, instead of using a man-made material in a standard shape(i.e. titanium mesh or porous polyethylene implant with a genericshape)—which is commonly kept “on-the-shelf” in the operating room,exemplary embodiments of the presently described implant providepatient-specific solutions with much better computer-design and anear-exact skull reconstruction. Thus, using exemplary embodimentsdescribed herein, the volume of the skull and orbital skeleton have amuch better chance of remaining constant and preventing the patient fromdemonstrating an eyeball-orbital deformity post-op. Once the design ofupdated implant model 600 is finalized using the CAD software, apatient-specific craniofacial implant may be manufactured using any oneof many known manufacturing techniques, such as steriolithography,milling, and molding, for example. The implant can then be manufactured,for example, from alloplastic materials such as PMMA, MEDPOR®, and PEEK,or any other FDA-approved biomaterial.

Referring now to exemplary FIGS. 9A-C, a further exemplary embodimentmay be shown and described. Here, an anterior boundary 902 of apre-existing skull and face 900 defect 901 in need of a customizedcranial implant may be shown in FIG. 9A. In this embodiment, however,and unlike previously known cranial implants, there is an extraextension of material 906 that goes above the intact skull and facialbone anteriorly to abut the lateral orbital rim (LOR) and fills in thearea around the zygomatico-frontal (ZF) suture 903, as shown in FIG. 9B.This embodiment can reflect a novel method of augmenting the soft tissuedeficiency secondary to atrophied muscle and fat following a previousneurosurgical procedure when compared to previous methodologies thatonly replaced cranial bone defects. A model 904 of a cranial implant maybe formed with extension area 906. An exemplary view of the dual-purposecustom cranial implant 908 as implanted can be seen in FIG. 9C.

In still another exemplary embodiment, and referring now to exemplaryFIGS. 10A-10C, another custom cranial implant may be shown anddescribed. As seen in FIG. 10A, an inferior boundary 1002 of apre-existing skull and facial 1000 defect 1001 in need of a customizedcranial implant may be shown. The custom cranial implant 1008 in thisexemplary embodiment, unlike previous cranial implants, can be designedand have a designated placement position that does not have any plannedcontact to the left inferior portion of the cranial defect 1001. Inother words, the implant can attach to approximately 85%-90% ofsurrounding bone or bone defect edges (superior, anterior and posterioronly), versus previous cranial implants which required attachment to100% bone defect edges (previous attachment methods and designs includedthe inferior edge as well). Similar to the above, in FIG. 10B, a modelmay be formed with an implant 1004 and extension region 1006. Then, andfurther to this example, the cranial implant 1008 can have a temporaltrim window 1010. The temporal trim window 1010 can allow for the“flaring out” of the inferior portion, for example to a consistent,pre-defined lateral projection point 1006 tangential to the plum line ofthe zygomatic arch (represented as the vertical plum line 1009 in FIG.10C) “Flaring out” is shown in attached FIG. 10D on the patient's rightside to camouflage the soft tissue deficiency, as opposed to thepatient's left side—which shows a “tapering in” shape consistent withthe contralateral, unaffected temporal bone. This can correct an/orprevent a temporal hollowing deformity along the lateral face andpterional skull region.

Additionally, the implant 1008 as described in this exemplaryembodiment, can allow for important space for the temporalis musclebeneath temporal window 1010 to remain below or underneath the customimplant 1008 and temporal trim window 1010 and remain undisturbed, inparticular when compared to previously cranial implant designs. In thoseprevious design, the surgeon performing the implant surgery would firstmobilize the “scarred in” tissue away from the brain and then repositionit to the outside of the cranial implant or perform resection ifdevascularized after mobilization. With the present embodiment, thesurgeon performing the implant surgery can leave muscle or tissue as-is,or otherwise have it stay the same as the condition it was found inprior to the surgery (assuming no other health risks or anomalies). Withthe present cranial implant, the surgeon can simply implant thedual-purpose cranial implant above the muscle and utilize contact to theanterior, posterior, and superior bone edges, without need for theinferior edge, which provides numerous benefits. First, it prevents riskof ischemia to the brain if and when new blood vessels (i.e.neoangenesis) formed between the muscle and brain in the interim leadingup to secondary cranioplasty surgery. Second, it saves significantoperative time, expertise, and effort by the surgeon unlike prior artmethods which a surgeon required to perform delicate mobilization.Further, it provides a durable, time-tested, consistent,computer-designed solution to restoring and replacing the missing softtissue, versus the eventual atrophy and shrinking of temporal tissuewhen mobilized and affixed to the outside of prior art skull implants.These three exemplary advantages help to minimize surgery-related costs,operative times, and surgical effort—which is a major advance for thespecialty. Additionally, this new design result in an extra extension ofmaterial that goes above the intact muscle to fill in missing fat and/ormuscle but at the same time has a trim window to prevent muscleimpingement, pain and/or chewing discomfort. Of note, prior art implantdesigns did not have extraneous onlay extensions and/or augmentedsections for temporal restoration.

Further, exemplary embodiments include the temporal trim window as seenin exemplary FIG. 10C, which allows a surgeon to avoid impingement ofthe temporalis muscle once left undisturbed, so that there is no orlimited pain associated with this cranioplasty procedure. For example,the patient will not experience pain during post-operative chewing.Additionally, as in contrast to previous designs and methods, thetemporal trim window makes for a much more durable, time-lastingreconstruction since the man-made biomaterial will hold its shapeindefinitely, as opposed to the constant shrinkage of mobilized tissueseen with prior art techniques. Unlike previous implant designs wherethe surgeon had to mobilize the muscle off the brain and attach it tothe outside of the implant, the muscle would typically atrophy over timeand the patient would then lose their desired facial symmetry and have avisible deformity after cranial implant surgery (i.e. cranioplasty). Incontrast, by leaving the muscle down in its scarred position by way ofthe present embodiment, and using the augmented/flared cranial implantdesign, the implant has a long-lasting shape that avoids occurrences ofmuscle atrophy or otherwise avoids a breakdown like in the mobilizedmuscle. This is because the material, versus muscle, holds better formwith time and, as a result, avoids long term or long-lasting negativeeffects on the patient.

For example, utilizing exemplary embodiments described herein, aftermore than 20-50 years, the implant will still have the same desiredshape and fitment. When compared with the prior art, this is highlydesirable as the prior art methodologies where the mobilized muscleultimate atrophies and leaves the patient with facial asymmetries andvisible deformities known as temporal hollowing or temporal wastingdeformities.

In exemplary FIGS. 11A-D, further exemplary embodiments may be shown. Inparticular, the temporal trim window 1010 can extend along line 1011from the zygomatic-frontal suture line area 1007 (also known as the “Z-Fsuture area”) to the zygomatic process of the temporal bone 1013. Thus,along line 1011, it can be known and/or determined where to start thetemporal trim window 1010. In the exemplary embodiments, the temporaltrim window is an additional advancement in the shape and design ofcustomized cranial implants. In previously exemplary embodiments of thisimplant design, there was excess material used for soft tissueaugmentation around the entire inferior portion. However, the presentexemplary embodiments provide a better way which can save additionaltime, reduce a demand for hand-eye artistry in the operating room, andalso provide a method to prevent temporalis muscle impingement. Inparticular, while previous exemplary embodiments had an augmented areawithin the caudal portion, it's the implant's shape towards the bottomwould consistently impinge the temporalis muscle and requireintra-operative modification using a hand-held drill (i.e. burr). Assuch, present embodiments, using a recent advance, is that we can savethe entire intra-operative, burr modification process by adding anadditional step to the virtual implant design phase usingcomputer-assisted design/modeling (CAD/CAM). The additional step in theimplant design process employs a vector line being drawn between thezygomatic process of the temporal bone and the zygomatic-frontal sutureof the lateral orbital rim at the very end of the design phase, as alocation for material removal. By connecting a virtual line betweenthese two consistent anatomical points, the designer can consistentlytrim the caudal portion of the augmented implant as to preventtemporalis muscle compression and all related symptoms, such as trismusand/or pain. It has been found that the superior portion (i.e. superiorhalf) of the convex augmented area can be all that is needed to correctand/or prevent the temporal hollowing deformity, and that the inferiorportion (i.e. inferior half) may not be needed at all and may be just anadditional step in the operating room. Previous exemplary embodimentsthus included unneeded operative time (e.g. an extra 30 minutes),additional expense for the drill and drill bit, and further hand-eyecoordination with artistic judgement from the surgeon for an idealresult, as opposed the current exemplary embodiments now described whichcan utilize computer-design modifications.

Turning now to exemplary FIGS. 12A-C and 13A-C, further exemplaryembodiments of a custom cranial implant 1008 with a temporal trim window1010 may be shown and described. In these exemplary embodiments, theline 1011 in FIGS. 12A-C provides an exemplary before view and line 1012in FIGS. 13A-C provides an after view where material is removed to makeroom for undisturbed temporalis muscle scarred down to the brain at thetime of a cranial implant. Such exemplary drawings provide furtherinformation related to the exemplary embodiments shown previously.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is, therefore, to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

What is claimed is:
 1. A method of preparing a facial or craniofacialimplant for filling a pre-existing bony void following craniectomy in acraniofacial region of a patient and for replacing facial soft tissue asa single-stage reconstruction, comprising: creating a three-dimensionalmodel of a cranial and/or facial region having a bony void; based on thethree-dimensional model, creating an implant model configured to replacethe bony void in the cranial and/or facial region, the implant modelfurther comprising an extension of material that goes above an intactskull region to fill in an area suffering nearby soft tissue atrophy asan onlay extension to prevent and/or correct visible deformity andasymmetry, and forming a temporal trim window on the implant model,wherein the temporal trim window is configured to allow for thetemporalis muscle beneath the temporal trim window remain below andundisturbed during the implant surgery.
 2. The method of claim 1,wherein the onlay extension is around the zygomatico-frontal suturealong the temporal fossa abutting the lateral orbital rim.